Magma evolution of the Sete Cidades volcano, São Miguel, Azores.

Beitrag in einer Fachzeitschrift
(Originalarbeit)


Details zur Publikation

Autorinnen und Autoren: Beier C, Hansteen T, Haase K
Zeitschrift: Journal of Petrology
Verlag: Oxford University Press (OUP): Policy B - Oxford Open Option A
Jahr der Veröffentlichung: 2006
Band: 47
Seitenbereich: 1375-1411
ISSN: 0022-3530
Sprache: Englisch


Abstract


The Sete Cidades volcano (São Miguel, Azores) is situated at the eastern end of the ultraslow spreading Terceira rift axis. The volcano comprises several dominantly basaltic pre-caldera eruptions, a trachytic caldera-forming stage and a post-caldera stage consisting of alternating trachytic and basaltic eruptions. The post-caldera flank lavas are more primitive (>5 wt % MgO) than the pre-caldera lavas, implying extended fractional crystallization and longer crustal residence times for the pre-caldera, shield-building lavas. Thermobarometric estimates show that the ascending alkali basaltic magmas stagnated and crystallized at the crust-mantle boundary (∼15 km depth), whereas the more evolved magmas mainly fractionated in the upper crust (∼3 km depth). The caldera-forming eruption was triggered by a basaltic injection into a shallow trachytic magma chamber. Lavas from all stages follow a single, continuous liquid line of descent from alkali basalt to trachyte, although slight differences in incompatible element (e.g. Ba/Nb, La/Nb) and Sr isotope ratios imply some heterogeneity of the mantle source. Major and trace element data suggest similar partial melting processes throughout the evolution of the volcano. Slight geochemical differences between post- and pre-caldera stage lavas from the Sete Cidades volcanic system indicate a variation in the mantle source composition with time. The oxygen fugacity increased from the pre-caldera to the post-caldera stage lavas, probably as a result of the assimilation of crustal rocks; this is supported by the presence of crustal xenoliths in the lavas of the flank vents. The lavas from the Sete Cidades volcano generally have low Sr isotope ratios; however, rocks from one post-caldera vent on the western flank indicate mixing with magmas resembling the lavas from the neighbouring Agua de Pau volcano, having higher Sr isotope ratios. The different magma sources at Sete Cidades and the adjacent Agua de Pau volcano imply that, despite their close proximity, there is only limited interaction between them. © 2006 Oxford University Press.



FAU-Autorinnen und Autoren / FAU-Herausgeberinnen und Herausgeber

Beier, Christoph PD Dr.
Lehrstuhl für Endogene Geodynamik
Haase, Karsten Prof. Dr.
Lehrstuhl für Endogene Geodynamik


Einrichtungen weiterer Autorinnen und Autoren

GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel


Zitierweisen

APA:
Beier, C., Hansteen, T., & Haase, K. (2006). Magma evolution of the Sete Cidades volcano, São Miguel, Azores. Journal of Petrology, 47, 1375-1411. https://dx.doi.org/10.1093/petrology/egl014

MLA:
Beier, Christoph, Thor Hansteen, and Karsten Haase. "Magma evolution of the Sete Cidades volcano, São Miguel, Azores." Journal of Petrology 47 (2006): 1375-1411.

BibTeX: 

Zuletzt aktualisiert 2018-09-08 um 12:38